1. Field of the Invention
The invention relates to eye viewing devices in general and specifically to a hand-held eye viewing device that is adapted to be readily moved into an operative position relative to a patient""s eye.
2. Background of the Prior Art
Many types of eye viewing devices require a certain positioning relative to a patient for proper operation. Retinal viewing ophthalmoscopes, in particular should be positioned at a certain radial displacement, angular orientation and axial standoff position relative to a patient""s eye for proper operation. The task of moving a retinal viewing ophthalmoscope into an operative position relative to an eye is particularly challenging given that in order to provide viewing of different areas of a retina, such devices should be moved between various angular orientations relative to an eye while maintaining certain radial displacement and axial standoff positions.
The positioning of commercially available hand-held eye viewing devices is customarily controlled entirely by the hand-eye coordination of a physician. During use of a known retinal viewing ophthalmoscope, for example, a physician manually moves the device into an operative position depending upon the image of the retina generated by the device""s viewing system at the physician""s retina.
Limitations have been observed with this method of positioning an eye viewing device. First, physicians using certain commercially available eye viewing devices have faced difficulty in positioning such devices in an operative position. The difficulty faced in achieving an operative position varies depending upon the particular eye viewing device. It is particularly challenging to position retinal viewing ophthalmoscopes relative to an eye since light rays of both the illumination and imaging system of such devices must pass through a patient""s pupil.
In general, the more challenging the task of achieving an operative position, the more difficult the task is of maintaining that operative position once it has been achieved. An operative position of certain eye viewing devices can be lost, for example, with small disturbances in the radial displacement position of the device relative to an eye.
There is a need for an eye viewing device which is adapted to be readily positioned in a desired radial displacement, angular orientation and axial standoff position relative to a patient, and which is adapted to be readily maintained in that desired radial displacement, angular orientation and axial standoff position once that position is attained.
According to its major aspects and broadly stated the invention is an eye viewing device adapted to be readily positioned in an operative position relative to an eye.
An eye viewing device according to the invention includes an eye cup having patient end adapted to be received at an eye orbit of a patient, the eye orbit being generally defined by an eyebrow and upper cheekbone of a patient. In one aspect of the invention, the outer diameter of the patient end of the eye cup is sized to correspond to a patient""s eye orbit. Because a center of a patient eye is located substantially at the center of an eye orbit, the sizing of the patient end outer diameter corresponding to an eye orbit operates to aid in the radial displacement positioning of the device.
In another aspect, the eye cup is made deformable so that contact of the eye cup with a patient alerts a physician that the device is approaching an operative axial standoff position. Making the eye cup deformable also enhances patient comfort.
In yet another aspect of the invention, the eye cup is made so that the eye viewing device can pivot about a pivot point near the patient end of the eye cup to allow adjustment of the eye viewing device""s angular orientation position relative to an eye to visualize various areas of the retina. Forming the eye cup so that the eye viewing device pivots about a pivot point toward the eye cup""s patient end allows adjustment of an eye viewing devices""s angular orientation without substantial disruption of the positioning of the device""s illumination and viewing axes relative to a pupil center (i.e., without disruption of the radial position) and therefore without movement of the device from an operative position.
In addition to aiding in the positioning of an eye viewing device relative to a patient, the eye cup prevents ambient light rays from reaching a patient""s eye, thereby substantially eliminating sources of external glare. Furthermore, because the eye cup allows the eye viewing device to be stabilized against an eye orbit during eye viewing, the eye cup eases the task of maintaining an operative viewing position after such an operative position is achieved.
These and other details, advantages and benefits of the present invention will become apparent from the detailed description of the preferred embodiment hereinbelow.